The present invention relates to latch bolt mechanisms, and particularly to latch bolt deadlocking mechanisms useful in both cylinder locks and tubular locks.
In certain known latch bolt mechanisms, the structure installed in the latch bolt for controlling the operation of the deadlocking tumbler includes several separate parts. For example, U.S. Pat. No. 4,318,558 to Best et al discloses such a structure having a first subassembly for releasing the deadlocking tumbler during retraction of the latch bolt. In addition, a separate second subassembly is provided for normally holding the deadlocking tumbler in a release position until the latch bolt is engaged in a strike plate upon closure of the door carrying the latch bolt mechanism. As shown best in FIGS. 6 and 9 of the Best et al '558 patent, the first subassembly includes a tailpiece 70 and a cam member 84, while the second subassembly includes an auxiliary bolt 50 and a release cam 108.
One object of the present invention is to reduce the number of separate parts needed to control the operation of a deadlocking tumbler, thereby reducing the cost of manufacturing and increasing the operating life of the control mechanism.
According to the present invention, an improved latch bolt deadlocking assembly is provided. The assembly includes a housing, an elongated latch bolt movable along its longitudinal axis in the housing between projected and retracted positions, and control means for selectively deadlocking the latch bolt to retain the latch bolt in its projected position. The control means is movable between a deadlocking position blocking movement of the latch bolt toward its retracted position and a release position permitting movement of the latch bolt toward its retracted position. The latch bolt is formed to include guide means extending along the length of the latch bolt for guiding the control means during movement between its deadlocking and release positions.
In preferred embodiments, the control means includes a deadlocking tumbler and an auxiliary bolt. The deadlocking tumbler is movable relative to the latch bolt between a first position deadlocking the latch bolt to retain the latch bolt in its projected position and a second position releasing the latch bolt to permit movement of the latch bolt toward its retracted position. The auxiliary bolt controls the position of the deadlocking tumbler. In operation, the auxiliary bolt slides on the latch bolt in a direction substantially parallel to the longitudinal axis of the latch bolt between a projected position holding the deadlocking tumbler in its second position and a retracted position permitting movement of the deadlocking tumbler to its first position.
The latch bolt includes forward and rearward sections which cooperate to provide the guide means. Shallow groove means is formed in the forward section of the latch bolt and configured to slidably receive and support the auxiliary bolt in its projected position. A spaced-apart pair of guide walls is provided in the rearward section and configured to slidably receive and support the auxiliary bolt in its retracted position. The forward ends of the guide walls are desirably connected to the rearward end of the shallow groove means. Illustratively, the guide walls are symmetrically beveled to converge toward the longitudinal axis of the latch bolt so that the auxiliary bolt is received and supported therebetween.
Also in preferred embodiments, the assembly further includes a tailpiece coupled to the latch bolt for selectively moving the latch bolt from its projected position to its retracted position. The auxiliary bolt desirably includes integral first cam means for holding the deadlocking tumbler in its release position while the auxiliary bolt is in its projected position. In addition, the tailpiece desirably includes integral second cam means for moving the deadlocking tumbler from its deadlocking position to its release position during retraction of the tailpiece.
One feature of the present invention is the formation of the latch bolt to include integral guide means extending along the length of the latch bolt for guiding the control means during movement of its deadlocking and release positions. In particular, the guide means guides the auxiliary bolt along a straight path as it moves between projected and retracted positions. As noted above, the auxiliary bolt controls the position of the deadlocking tumbler. In contrast to known latch bolt mechanisms, the novel configuration of the latch bolt itself provides the means for guiding and supporting the slidable auxiliary bolt. Such a feature advantageously reduces the number of parts needed to operate the deadlocking tumbler.
Additional objects, features, and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of a preferred embodiment exemplifying the best mode of carrying out the invention as presently perceived.